We have developed protocols to assess the physiology of isoolated leukocytes and leukocytes in blood. These protocols involve the analysis of cell function and the expression of surface receptors indicative of cell activation. We have examined the expression of adhesive markers in trauma patients (Fry). We are beginning to characterize the response of leukocytes in septic neonates to administration of GM-CSF (Ohls) and the response of leukocytes in breast cancer patients to the administration of taxol and its carrier (Rogelj).